If you don't mind taking forever and going through a ton of batteries. The 6V 4.5Ah battery has about 97KW of power in it. Each of the coin cell batteries in the mosquito racket circuit may only have 100W. Since you would need to increase the voltage of the 3V coin cell to at least 7 volts to charge the 6V battery, the amount of current available decreases as you increase the voltage. Also, the coin cell battery can only put out a limited amount of current (due to its size).